Zirchrome mineral dyeing process for producing cellulosic materials with a plurality of degradation resistance factors



US. en. s s2 United States Patent" ABSTRACT OF THE DISCLOSURE A practical method for producing' cellulosic materials with a pearl gray finish with a plurality of degradation resistance factors. This method has been designated the title Zirchrome Process, and reduces a multibath treatment to a single bath application wherein a hexavalent chromium compound and an inhibited reducer are applied with zirconyl ammonium carbonate, with or Without a fungicide and/or Wax. The reduction to a pearl gray colored mineral dyeing is effected by either a heat cure or simply by allowing the impregnated material to air dry. The finished cellulosic materials have an accepted coloration, microbiological degradation resistance, and water repellency. These characteristics are imparted to cellulosic materials, such as textiles, through a singlebath application.

A nonexclusive, irrevocable, royalty-free license in the invention herein described throughout the world for all purposes of the United States Government, with the power to grand sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to a process for imparting to cellulosic materials a mineral dyeing with resistance to actinic and biological degradation, while investing the treated material with hydrophobic characteristics. Specifically, this invention relates to a process for imparting to cellulosic materials resistance to degradation through a plurality of factors by the deposition of selected inorganic compounds in combination with zirconium and/ or waxes, through a single bath application. More specifically, this invention relates to the formation and subsequent in situ deposition of complex mineral deposits derived from chromium, zirconium, copper, and mercury, in cellulosic materials, to produce mineral dyeings and fungicidal mineral dyeings of said cellulosic materials for the purpose of greater protection from actinic degradation, microbiological degradation, and weathering in general. Among the great number of useful items which can be fabricated from the materials treated by process of the present invention the following items would be significantly improved: tobacco shade cloth, awnings, curtains, tents, tarpaulins, beach umbrellas, shoe liners, liferaft covers, sails, cording material, Army cotton garments, Navy cotton camouflage, tennis shoes, etc.

The prior art teaches the application of mineral dyeings by double decomposition wherein several baths and washings and then dyeings are commonly required to obtain the desired finish. In addition, the application of fungicides and water repellants have required separate pad-dry-cure procedures, separate from the mineral dyeings. By the method which is our present invention a revolutionary chemical mechanism is necessitated wherein a water solubl e hexavalent chromium compound is applied to cellulosic material in the presence of a reducing agent in the inhibited state, and caused to react on the said cellulosic material by removal of the inhibitor through dryice ing or curing, to deposit in situ a mineral dye composed of chromium and zirconium oxides.

A particularly attractive coloration is obtained inthe cellulosic final products of the present'invention. This coloration is in the form of a gray-green shade which has been accepted and desired by those skilled in the art, and industrially the shade of coloris known in the trade as pearl gray. We have reproduced this pearl gray coloration by the process of our invention on cellulosic textiles, obtaining in the treatedtextilesthe addedjfe atures of actinic degradation resistance, microbiologicaldegradation resistance, and water repellency. A significant able to impart the plurality of degradation resistance factors through a single bath application.

The main object of this inventionis to provide an improved pearl gray-fungicidal treatment for cellulosic textiles.

A second object of this invention is to provide an improved pearl gray fungicidally treated mineral dyed cellulosic material, with or without a wax finish, by a sirnple pad-dry-cure procedure.

A third object of this invention'is to reduce the need for excessive investment in equipment by reducing the stages or the number of baths which have been commonly employed in the current industrial pearl gray processing. A fourth object of this invention is to provide a process which requires less chemical and processing controls than those now commonly employed in the art.

A fifth object of the present invention is to provide a method wherein the mineral dyeing which yields the pearl gray colored finish of this invention is attained through room temperature curing simply by allowing the impregnated material to air dry.

In general our present invention can best be described as a process for imparting to cellulosic materials a pearl gray colored mineral dyeing having resistance to actinic degradation, resistance to microbiological degradation, and resistance to wetting, wherein the combined properties are obtained on the finished product from a singlebath application, comprising: i

(a) impregnating a cellulosic material with a mixture of two aqueous solutions consisting of:

Solution I, which contains about from 1% to 20% ammonium carbonate, sufiicient zirconyl ammonium carbonate to represent 0.7% to 3.0% ZrO in said Solution I, and about from 0.8% to 4.0% chromium metal in the form of a hexavalent chromium compound selected from the group consisting of sodium chromate, potassium chromate, sodium dichromate, ammonium chromate, ammonium dichromate, and calcium chromate, and

Solution II, which contains about from 10% to 40% of a reducing agent selected from the group consisting of sodium bisulfite, sodium hydrosulfite, and sodium metabisulfiite, wherein the said reducing agent is treated with sufiicient ammonium hydroxide or ammonium carbonate to produce a sodium ammonium sulfite solution (Solution II) and a :pH about from 7.5 to 9.0, to inhibit the potential reducing action wherein Solutions I and II are mixed in ratio of about 2:3, respectively;

(b) Removing the excess mixture of solutions from the impregnated cellulosic material to obtain about from 40% to 60% wet pickup,

(c) Drying the wet, impregnated cellulosic material for about from 3 to 5 minutes of time, at temperatures about from to C., using the longer drying times with the lower temperatures, and

(d) Curing the dry, impregnated cellulosic material for about from 2 minutes to 5 hours, at temperatures about from 25 to C., using the longer curing times with lower temperatures.

The process of this invention varies in the step (a),

above, when the reducing agent of Solution II is simply ammonium sulfite, and the wording of step (a) should then read thusly:

(a) Impregnating a cellulosic material with a mixture of two aqueous solutions consisting of:

Solution I, which contains about from 1% to 20% ammonium carbonate, sufiicient zirconyl ammonium carbonate to represent 0.7% to 3.0% ZrO in said Solution I, and about from 0.8% to 4.0% chromium metal in the form of a hexavalent chromium compound selected from the group consisting of sodium chromate, potassium chromate, sodium dichromate, ammonium chromate, ammonium dichromate, and calcium chromate, and

Solution II, which contains about from to 40% of reducing agent ammonium sulfite wherein the said reducing agent is treated with sufiicient ammonium hydroxide or ammonium carbonate to produce a pH about from 7.5 to 9.0, to inhibit the potential reducing action wherein Solutions I and II are mixed in ratio of about 2:3, respectively.

The reduction of hexavalent chromium compound with neutral or acidic reducing agentsi.e., sodium bisulfite in the presence of mineral acids has been known in the prior art. The reduction of hexavalent chromium compound by neutral or acidic reducing agent in the absence of mineral acid results in a gel of chromium hydroxide. This reaction does not occur under alkaline conditions.

The reaction of a neutral or acidic reducing agent i.e., sodium bisulfiite-with ammonium carbonate or ammonium hydroxide produces an alkaline inhibited reducer (sodium ammonium sulfite) which can be decomposed by drying or heating to regenerate sodium bisulfite. This instantly reduces the hexavalent chromium to chromium hydroxide (a mineral dye).

The use of neutral or acid sulfite reducers causes rapid reduction of the hexavalent chromium to trivalent chromium with gel formation, limiting the usefulness of such solutions for padding applications to textile materials. It is also apparent that an inhibited reducer such as herein disclosed can be used with soluble hexavalent chromium salts to produce mineral dyed fabrics through heat curing to remove the inhibitor. However, zirconium dioxide is necessary to obtain maximum resistance to weathering and leaching, and to complex and solubilize certain copper and mercury compounds which are dissolved in the inhibited hexavalent chromium compound in a water solution, these compounds are deposited as insoluble copper-zirconium and mercury-zirconium fungicidal compounds along with the mineral dyeing on drying or curing. When a paraffin wax emulsion (ammonium stearate emulsifier) is combined with the pad bath, a uniform bath results, which deposits mineral dyeing, fungicide, and wax repellent finish all at the same time from the same bath, within the fabric. Heating or drying deposits the insoluble mineral dye and fungicide into the fabric from the water phase, while the wax coats the fibers to produce a wax finish coating for water repellency. The wax may be incorporated into a single bath, or may be applied to the single bath mineral dyed fabric after curing, washing, and drying.

According to the process of our present invention, a water soluble chromate or hexavalent chromium salt, such as potassium chromate, sodium chromate, sodium dichromate, or the like, is dissolved in water containing an excess of ammonium carbonate. Zirconyl ammonium carbonate (10% ZrO solution is added to the chromate and ammonium carbonate solution to produce a stable stock solution, designated as Solution I of a two solution system. A second solution (Solution II) is prepared by dissolving a reducing agent, such as sodium metabisulfite, sodium hydrosulfite, ammonium sulfite, or the like, in water, and adding ammonia or ammonium carbonate to the solution until a pH of 7.5 to 9.0 is attained. This inhibits the reducing properties of the sulfite solution, and

is the key to the prevention of gel formation, which is essential for a single pad bath process.

The equations pertinent to the preparation of Solution H are IIa or IIb. These merely show two methods used in preparing the inhibited sodium ammonium sulfite, and should not be taken to mean as limiting the invention to one of these equations.

(Ila) 2NaHSO (NH CO 2Na(NH )SO +H O+CO T (IIb) NHQOH NaHSO; NMNHOSO: H O

inhibited sodiumammonium sulfite, pH 7.5 to 8.5 This is designated as Solution II, the inhibited reducer. When solutions I and 11a or IIb are mixed, no evidence of reduction is evidenced. Paddings are made with this bath. On heating or drying, the inhibitor (NI-I is removed as follows, by loss of NH inhibited active reducer reducer The S0 from the (I-I50 radical is now an effective reducer for the hexavalent chromium, reducing the chromium to chromium oxide ultimately, producing a chromium-zirconia mineral dyeing with the zirconia from the decomposition of the zirconyl ammonium carbonate also present, and which decomposes as follows:

hydrated 1111301113 Previously described (US. Patent No. 3,291,635 (December 1966) fungicidal metal salt-zirconia work shows that copper borate, phenylmercuric salts, zinc borate, etc., many fungicidal metal salts, are soluble in zirconyl ammonium carbonate solutions and produce insoluble metal salt-zirconia deposits in fabric (fungicide finishes where copper and mercury are used). Consequently, adding copper or mercury-zirconyl ammonium carbonate water soluble complexes to Solution I produces a compatible clear solution which can be mixed with the inhibited reducer, Solution IIa or III), to produce a fungicidal mineral dyeing bath, when the chromium oxide-zirconia and the copper or mercury-zirconia deposits are produced together on heat curing, to form a fungicidal mineral dyeing. Copper metaborate may be dissolved directly in Solution I to produce the same effect, since zirconyl ammonium carbonate is present in Solution I to solubilize it. Furthermore, the addition of parafiin wax-emulsion to the bath of mixed Solution I and Solution 11 produces a compatible mixture, which produces the mineral dyeing, fungicide, and Wax finish on heat curing.

It is obvious that since all of these effects can be produced from a single pad and cure, the process is novel and requires a minimum of equipment, making it possible for numerous small textile mills to produce pearl gray colored mineral dyeings, where this has previously been impractical due to expensive processing steps. Furthermore, the in situ deposition of dye and fungicide gives greater penetration than surface deposit through double decomposition of a metal salt (reduced) with alkali hydroxide and soaps. The new process attributes better light screening since zirconia is an added light screener. The new process attributes algaecidal resistance since zirconia is an algaecide (US. patent Ser. No. 422,462 of Dec. 30, 1964). The copper-zirconia and mercury-zirconia fungicides are improved fungicides for cotton over the copper and mercury fungicides alone (Reference: Some Microbial Resistant Compounds of Zirconium and Their Effect on Cotton, TRJ., vol. 34, No. 4, March 1964). Hence, the novel and advantageous process herein described, shows great industrial potentiality and utility for improved industrial feasibility, demonstrating a revolutonary process for mineral dyeings in a field where the older conventional method has been outdated for the past one hundred years. It is to be designated as the Zirchrome Process, where zirconium acts as a fungicidal solubilizing component and a lock-on or laking ingredient when decomposed to zirconia in drying or heating with the reduced chromium compound, to produce a chromium oxide-zirconia deposit.

The following equations demonstrate the entire Zirchrome Process, with regard to formation of the inhibited reducer and heat decomposition of this compound (sodium ammonium sulfite) to reform an active sodium bisulfite reducer. This reformed sodium bisulfite reduces the water soluble hexavalent chromium compound (chromate) to trivalent chromium oxide (hydrated). The simultaneous heat decomposition of the zirconyl ammonium carbonate, also present, results in hydrated zirconia (ZrO -2H O) being deposited with the hydrated chromium oxide, and possibly as a single complex compound [(Cr O -ZrO -2H O], which is the zirchrome pigment of the mineral dyeing. A byproduct, sodium hydroxide, reacts with the carbon dioxide from the zirconyl ammonium carbonate decomposition, to form sodium bicarbonate (pH 7.0), illustrating that the fabric is always in contact with an alkaline or neutral medium, and therefore cannot be tendered by the chemical nature of the treatment.

Theoretical mechanisms for single bath mineral dyeing active reducer ate chromium oxide (hydrated) gray-white zirconyl amm onium hydrated zirconia carbonate zirchrome mineral dye ZNaOH 200: 2NaHCOa(pH 7.0)

EXAMPLE 1 A hexavalent chromium stock solution, Solution I (chromate), was prepared by mixing the following quantities of the indicated ingredients at room temperature until completely dissolved. A clear lemon-yellow colored solution with an ammoniacal odor was obtained. This solution was set aside to be used later as needed.

200 grams ammonium carbonate crystals 180 grams sodium or potassium chromate granulated crystals 540 grams distilled water 200 grams zirconyl ammonium carbonate (10% ZIOg) sol.

1120 grams=960 ml.1 qt. chromate (Sol No. 1)

EXAMPLE 2 An inhibited reducer stock solution, Solution IIa, was prepared with ammonium carbonate by mixing the following quantities of the indicated ingredients at room temperature until completely dissolved. After the reaction, colorless solution with a faint ammoniacal odor was obtained. This solution was set aside to be used later as needed, and contains sodium ammonium sulfite.

240.00 grams Na S O (sodium metabisulfite) powder 860.00 grams distilled water 110.00 grams ammonium carbonate crystals 1210.00 grams=964 ml.1 qt. (inhibited reducer) EXAMPLE 3 Solutions I and II prepared in Examples 1 and 2 above were mixed in the following proportions and used in padding baths for treating cellulosic fabrics. The mixed solutions were clear and produced a brownish-yellow liquid with an ammoniacal odor. The mixed solutions were stable for about 26 hours before a gel was produced.

Parts Solution No. I by volume 20 Solution No. II by volume 30 EXAMPLE 4 Four samples of 9-ounce scoured and bleached cotton duck (4" x 6") each were cut. Each of the pieces was padded through the mixed solution of Example 3, to a wet-pickup of 60%. One piece was allowed to air dry. The second piece was dried at 130 C. in an oven for 3 minutes, removed from the oven, and allowed to air cure for 5 hours. The third piece was cured at 150 C. for 4 minutes. The fourth piece was dried in an oven at C. for 3 minutes, followed by 150 C. for 3 minutes cure in the oven. In the four instances the dried samples cured to produce gray-mineral dyeings, which were not afiected when washed. The wet padded fabrics were yellow in color and converted to insoluble gray-green mineral dye deposits on the fabric in curing.

EXAMPLE 5 An inhibited reducer stock solution, Solution IIb, was prepared using ammonium hydroxide in place of ammonium carbonate, by mixing the following quantities of the indicated ingredients at room temperature until completely dissolved. This solution produces no carbon dioxide gas, and the solution of sodium ammonium sulfite is more easily and rapidly prepared.

Grams Na S O (sodium metabisulfite) powder 240 Distilled water 730 28% ammonium hydroxide 240 Modified stock solution (inhibited reducer) 1210 EXAMPLE 6 Five cotton samples of different construction were dyed by the process of the inventors as follows: Sections each measuring 4" x 30" of cotton twill, cotton drill, 7- ounce cotton duck, ll-ounce cotton duck, and lined 8.9- ounce cotton duck were cut, and each padded separately with a pad bath solution consisting of 20 parts of the solution No. I of Example 1 (chromate) mixed with 30 parts of Solution II, Example 2 (inhibited reducer). The fabric samples were conventionally padded with two dips and two nips, to a wet pickup of 80%, dried at C. for 2 7 minutes, and cured at 150 C. for 3 minutes. All fabrics dyed uniformly with zirchrome pigment.

EXAMPLE 7 Varying the ratio of Solution I to Solution T1 Four samples of 9-ounce cotton duck (scoured and bleached) were treated separately with 4 solutions of varying ratios. The 4 samples were wetted and blotted with the solutions (a), (b), (c), and (d), described below. Each of the wetted and blotted samples was divided into two parts. In one case the first four portions were allowed to air dry for 5 hours. The second portion of each of the 4 samples was oven cured at 145 C. for 4 minutes. The dyeings of the air dried samples were equal in coloration to the dyeings of the oven cured samples relative to the respective padding ratios listed below:

(a) 20 ml. sol. No. K and 20 ml. sol. No. -IIyellowish gray-green mineral dyeing (b) 20 ml. sol. No. I and 30 ml. sol. No. II-blue-green mineral dyeing (c) 20 ml. sol. No. I and 25 ml. sol. No. IIbluish-graygreen mineral dyeing (d) 20 ml. sol. No. I and 40 ml. sol. No. IIgreen mineral dyeing EXAMPLE 8 Determination of quantity of ammonium carbonate or ammonium hydroxide necessary to inhibit sodium bisulfite reduction Two grams (2.0 gm.) of sodium metabisulfite were dissolved in 10 ml. of distilled water and treated with weighed amounts of ammonium carbonate crystals to produce a pH of 7.5. This required 0.92 gm. of the carbonate. Up to 1.5 gm. of the carbonate produced 9.0 pH values and can be used if desired.

Two grams (2.0 gm.) of sodium metabisulfite were dissolved in 10 ml. of distilled water and treated with weighed amounts of 28% ammonium hydroxide to a pH of 7.5. This required two grams (2.0) of ammonium hydroxide. Up to 2.2 grams of ammonium hydroxide produced 9.0 pH values and can be used. Higher amounts (3.0 gm.) produces excess hydroxide ions and tends to precipitate zirconia from the mixed bath of Solution No. I and Solution No. II.

Mixed reducer and chromate solutions showed that the chromate was not reduced when the pH was 7.5 or higher in the presence of ammonium carbonate or ammonium hydroxide.

EXAMPLE 9 Quantities of sodium metabisulfite required for controlled chromate reduction Holding the chromate constant and varying the bisulfite the following chart illustrates the results obtained upon the deposition of the mineral dyeing on cotton fabric samples.

Chromate (lbs.) Bisulfite Obs.) Shade obtained 6 Gray-green. 5. 0 Greenish-gray. 4. Yellowish-gray. 6.8 Blue-gray to green.

.the bath was applied to cotton lO-ounce duck fabric and cured.

8 EXAMPLE 10 Addition of fungicide (copper metaborate) to formulation Copper metaborate may be incorporated in the dye bath at concentrations about from 0.01 percent to 2.0 percent copper calculated as metal. A quantity of copper metaborate powder was Weighed and dissolved in a portion of the Solution I (Example 1) to give the desired copper content in the bath produced when Solution No. 1 was mixed with Solution No. 11 (Example 2); in this instance the following quantities were mixed to obtain the solution which was padded onto cotton duck, twill, and drill.

2 gallons Solution No. 1 (previously described) 200 gm. of copper metaborate powder Stir until dissolved (yellow-green solution) 3 gallons of Solution No. II

EXAMPLE 11 An alternate fungicidal mixture The fungicidal solution was prepared by mixing ingredients (a), (b), and (c) in the quantities indicated below.

(a) 2 gallons Solution No. I

(b) 50 lbs. copper metaborate-zirconyl ammonium carbonate solution 3.2% Cu (See US. Patent 3,291,635, issued Dec. 13, 1966) (c) 3 gallons Solution No. II

This solution was found to contain 1.60% copper as metal. The fabric acquired 0.48% to 0.80% copper add-on after pad and cure with a wet pickup of 30% and 50%, respectively. From earlier work it has been determined that only 0.08% copper content is sufiicient to obtain good weathering protection. For ease in mixing it was observed that the ingredients must be added in the order indicated above-(a), first; (b), second; and (c), third.

EXAMPLE l2 Incorporating phenylmercury salt for a fungicidal mineral dyeing A phenylmercury salt was dissolved in zirconyl ammonium solution and added to the mixture of Solutions I and II (Examples 1 and 2 above) to produce a mercurymineral dyeing with fungicidal characteristics. The formulation is as follows:

20 parts by volume Solution I 30 parts by volume Solution II 2 parts by volume (phenylmercury salt in triethanolamine or zirconyl ammonium carbonate solution) 1 Lactate, acetate, or propionate.

The application of this fungicidal pad mixture dyeing to cotton produced gray-green mineral dyeing with a fungicidal phenylmercury residue.

EXAMPLE l3 Incorporating wax into the pearl gray mineral dyeing single padbath A single pad bath emulsion containing the indicated quantities of Solutions I and II (Examples 1 and 2) was mixed with a paraflin wax emulsion and was prepared as follows:

Gal.

Solution No. I 1.5

Solution No. II 2.5 20% paraflin wax emulsion paste (ammon.

stearate base) 1.0

EXAMPLE 14 Mineral dyeing followed by wax emulsion padding A mixture containing 2 gallons of Solution No. I (Example 1) with 3 gallons of Solution II (Example 2) was well mixed and applied to several cotton fabric samples as follows:

Gal. Solution No. I (with or without fungicide) 2 Solution No. II 3 Three cotton fabric samples were padded through the above single bath, after which, one of the fabrics was air cured, one was oven dried and then oven cured, and one was oven cured directly. The three cured fabrics were then washed to remove soluble byproduct salts, and then given a conventional wax emulsion bath padding where the wax bath contained 8 pounds of wax per 100 lbs. of wax emulsion bath. The wax emulsion bath was followed by an oven dry-cure at 130 C./3 to 4 minutes for all three fabrics. Good water repellency resulted with each fabric.

EXAMPLE 15 Mineral dye development with loss of ammonia A solution containing 20 parts of Solution No. I (Example 1) and 30 parts of Solution No. II (Example 2) was prepared. The pH of the solution was about 7.5 to 8.0. A sample of 9-ounce scoured cotton duck was impregnated in this solution. The impregnated fabric was allowed to air cure about 15 hours, hanging from a line. A check in pH was maintained in the following manner: Laboratory pH paper (Hydrion) was wetted with distilled water and placed near the fabric at intervals of 1 hour making sure that the paper would not touch the treated fabric throughout the period of five hours. Ammonia (NH continued to be liberated, while the mineral dye (gray-green) developed. Complete reduction had occurred, and a maximum intensity gray-green mineral dye deposited at the end of hours. Fabric still showed a slight liberation of NH as evidenced by the pH paper. After 10 hours, the liberation of NH was barely detectable with pH paper. After hours, when liberated ammonia ceased, the sample was touched with moistened (distilled water) pH paper, and showed a pH of 7.0. Consequently, no acid residual is left in the fabric, and curing was associated with loss of ammonia.

EXAMPLE 16 To investigate the interchangeability of sodium chromate, ammonium chromate, ammonium dichromate, calcium chromate, potassium chromate, and sodium dichrom- 10 ate in the Solution No. I formulation, the following procedures were carried out:

Six separate solutions were prepared wherein each one of these ingredients was mixed separately in the preparation of Solution I. Solution No. II was prepared with ammonium carbonate and ammonium hydroxide-also in separate formulations. The previously reported ratios of Solution No. I to Solution No. H were observed in preparing these new baths, using each of these preparation(s) with both formulations of the inhibited Solution No. 11. Increasing number of checks were made employing cotton samples and in every instance the single bath was identical and the results the same with regard to the cotton mineral dyeings.

From this observation it was concluded that all water soluble hexavalent chromium compounds were suitable for this process.

EXAMPLE 17 Use of ammonium chromate or 'bichromate in Solution I Solution I was prepared using 16% ammonium chromate and mixed with sodium ammonium sulfite (Solution II).

Solution I was prepared using 16% ammonium bichromate and mixed with sodium ammonium sulfite (Solution II).

Cotton fabrics were treated with each of these mixtures. Substitution of ammonium hexavalent chromium compounds in Solution I produced an air cured mineral dyeing and an oven cured mineral dyeing which was satisfactory in each instance.

EXAMPLE 18 Use of sodium hydrosulfite as inhibited reducer Using the formulation of Example 17 (but substituting sodium hydrosulfite as reducer in place of sodium metabisulfite in Solution 11). Final reduction from mixture of Solutions No. I and II, produced a deep bluegreen mineral dyeing when applied to cotton fabrics and heat cured.

EXAMPLE 19 Limitation on concentration of mineral dyeings Using 2 gallons of Solution I (Example 1) with 3 gallons of Solution II (Example 2) these were mixed and applied to samples of twill, drill, and 8, l0, ll-ounce duck cotton fabrics to obtain a 50%60% wet pickup. This yielded 1.0% to 1.2% chromium metal add-ons with 0.4% ZrO (The Zr0 can be increased to 6.2% in solution and the chromium to 8% in solution by increasing the chromate and zirconyl ammonium carbonate and proportionately reducing the water.)

Concentrations of 0.9 to 2% chromium as metal on the fabric are preferred; however, the procedure observed in this example is satisfactory for good coloration and fabric protection and higher ranges are not desirable due to the increase in cost of the application.

EXAMPLE 20 Soil burial resistance of the treated cotton fabrics Cotton duck, twill, drill and special lined duck were conventionally padded and oven cured to produce dyed and fungicidally mineral dyed fabrics, using the formulations for pearl gray mineral dye form a single pad bath herein described. The chromium, zirconia, and copper add-ons were 0.9% chromium, 0.4% ZrO and 0.08% Cu where the copper metaborate fungicide was incorporated. The untreated controls (fabrics described) rotted out in one week. The mineral dyed fabrics alone remained intact for two weeks, and the fungicidal mineral dyed fabrics showed three weeks protection.

1 1 EXAMPLE 21 Weathering of samples which were treated with a copper metaborate formulation Several 9-ounce cotton duck samples were treated with a formulation of zirchrome bath, containing a fungicide as follows:

The solution contained 0.34% copper as metal, 2% chromium as metal, and 0.8% ZrO A similar bath was prepared without the copper metaborate fungicide. Wet pickup was 50%. Duplicate samples were prepared and padded with the solution which excluded the fungicide dried and cured and exposed to weathering. After one year of outdoor weathering, the chrome-zirconia treated samples were found to retain excellent color and to retain 90% of their strength. The untreated controls show moderate to heavy mildew and algae growth and retained only 30% of the original strength. The samples which contained the fungicide stated above had excellent color retention, no mildew or algae growth and retained 100% of the original strength over this same period of exposure and under the same conditions of exposure.

EXAMPLE 22 Use of ammonium sulfite as a reducer in Solution II Ammonium sulfite was used in preparing Solution II (Ref. Example 2) in place of sodium metabisulfite. This solution was mixed with Solution I (Example 1) and applied to a cotton 10-ounce duck fabric. A wet pickup of 50% was obtained. The fabric was allowed to air dry for 10 hours. The finished fabric was gray-green mineral dyed and the coloration obtained was the same as with sodium bisulfite reduction.

The advantage of using ammonium sulfite as a reducer can be seen as shown below:

A (NHOZSO; ZNHaT H2503 Active reducer We claim:

1. A process for imparting to cellulosic materials a pearl gray colored mineral dyeing having resistance to actinic degradation, resistance to microbiological degradation, and resistance to wetting, wherein the combined properties are obtained on the finished product from a single-bath application, comprising:

(a) impregnating a cellulosic material with a mixture of two aqueous solutions consisting of:

Solution I, which contains about from 1% to 20% ammonium carbonate, suflicient zirconyl ammonium carbonate to represent 0.7% to 3.0% ZrO in said Solution I, and about from 0.8% to 4.0% chromium metal in the form of a hexavalent chromium compound selected from the group consisting of sodium chromate, potassium chromate, sodium dichromate, ammonium dichromate, and calcium chromate, and

Solution II, which contains about from 10% to 40% of a reducing agent selected from the group consisting of sodium bisulfite, sodium hydrosulfite, and sodium metabisulfite,

wherein the said reducing agent is treated with sufficient ammonium hydroxide or ammonium carbonate to produce a sodium ammonium sulfite solution (Solution II) and a pH about from 7.5 to 9.0, to inhibit the potential reducing action wherein Solutions I and II are mixed in ratio of about 2:3, respectively;

(b) removing the excess mixture of solutions from the impregnated cellulosic material to obtain about from 40% to 80% wet pickup;

(c) drying the wet, impregnated cellulosic material for about from 3 to 5 minutes of time, at temperatures about from 90 to 130 C., using the longer drying times with the lower temperatures; and

(d) curing the dry, impregnated cellulosic material for about from 2 minutes to 5 hours, at temperatures about from 25 C. to 160 C., using the longer curing times with the lower temperatures.

2. A process for imparting to cellulose materials a pearl gray colored mineral dyeing having resistance to actinic degradation, resistance to microbiological degradation, and resistance to wetting, wherein the combined properties are obtained on the finished product from a single-bath application, comprising:

(a) impregnating a cellulosic material with a mixture of two aqueous solutions consisting of:

Solution I, which contains about from 1% to 20% ammonium carbonate, sufficient zirconyl ammonium carbonate to represent 0.7 to 3.0% ZrO in said Solution I, and about from 0.8% to 4.0% chromium metal in the form of a hexavalent chromium compound selected from the group consisting of sodium chromate, potassium chromate, sodium dichromate, ammonium chromate, ammonium dichromate, and calcium chromate, and

Solution 11, which contains about fiom 10% to 40% of reducing agent ammonium sulfite,

wherein the said reducing agent is treated with sufficient ammonium hydroxide or ammonium carbonate to produce a pH about from 7.5 to 9.0, to inhibit the potential reducing action wherein Solutions I and II are mixed in ratio of about 2:3, respectively;

(b) removing the excess mixture of solutions from the impregnated cellulosic material to obtain about from 50% to wet pickup;

(c) drying the wet, impregnated cellulosic material for about from 3 to 5 minutes of time, at temperatures about from to C., using the longer drying times with the lower temperature; and

(d) curing the dry, impregnated cellulosic material for about from 2 minutes to 5 hours, at temperatures about from 25 C. to C., using the longer curing times with the lower temperatures.

3. The process of claim 1 wherein the hexavalent chromium compound is sodium chromate and the reducing agent is sodium bisulfite.

4. The process of claim 1 wherein the hexavalent chromium compound is potassium chromate and the reducing agent is sodium bisulfite.

5. The process of claim 1 wherein the hexavalent chromium compound is sodium dichromate and the reducing agent is sodium bisulfite.

6. The process of claim 1 wherein the hexavalent chromium compound is ammonium chromate and the reducing agent is sodium bisulfite.

7. The process of claim 1 wherein the hexavalent chromium compound is ammonium dichromate and the reducing agent is sodium bisulfite.

8. The process of claim 1 wherein the hexavalent chromium compound is calcium chromate and the reducing agent is sodium bisulfite.

9. The process of claim 1 wherein the hexavalent chromium compound is sodium chromate and the reducing agent is sodium hydrosulfite.

10. The process of claim 1 wherein the hexavalent chromium compound is potassium chromate and the reducing agent is sodium hydrosulfite.

11. The process of claim 1 wherein the hexavalent chromium compound is sodium dichromate and the reducing agent is sodium hydrosulfite.

12. The process of claim 1 wherein the hexavalent chromium compound is ammonium chromate and the reducing agent is sodium hydrosulfite.

13. The process of claim 1 wherein the hexavalent chromium compound is ammonium dichromate and the reducing agent is sodium hydrosulfite.

14. The process of claim 1 wherein the hexavalent chromium compound is calcium chromate and the reducing agent is sodium hydrosulfite.

15. The process of claim 1 wherein the hexavalent chromium compound is sodium chromate and the reducing agent is sodium metabisulfite.

16. The process of claim 1 wherein the hexavalent chromium compound is potassium chromate and the reducing agent is sodium metabisulfite.

17. The process of claim 1 wherein the hexavalent chromium compound is sodium dichromate and the reducing agent is sodium metabisulfite.

18. The process of claim 1 wherein the hexavalent chromium compound is ammonium chromate and the reducing agent is sodium metabisulfite.

19. The process of claim 1 wherein the hexavalent chromium com-pound is ammonium dichromate and the reducing agent is sodium metabisulfite.

20. The process of claim 1 wherein the hexavalent chromium compound is calcium chromate and the reducing agent is sodium metabisulfite.

21. The process of claim 2 wherein the hexavalent chromium compound is sodium chromate.

References Cited UNITED STATES PATENTS 2,035,527 3/1936 Brown et a1. 2,091,539 8/1937 White. 3,291,635 12/1966 Conner.

OTHER REFERENCES Conner et al.: Textile Research Jrn1., vol. 37, No. 2, pp. 94402, February 1967.

NORMAN G. TORCHIN, Primary Examiner.

J. E. CALLAGHAN, Assistant Examiner.

US. Cl. X.R. 117-1385, 139.5 

